In the Cambridge area from 1 January 1996 to 31 December 2002 (that is the period during which we had PSA data linked to cancer registry data), 8894 men had at least one PSA test, of whom 23% (2053) were 50–59 years, 30% (2701) were 60–69 years and 38% (3352) were 70–89 years. The gene discussed is KLK3; the disease is cancer.